On Wed, 8 Aug 2018 12:59:09 +0000 James Pearson james-p@moving-picture.com wrote:

James Pearson wrote:

...

I'm attempting to port an existing xinetd service from CentOS 6 to something equivalent with systemd for CentOS 7

The existing xinetd config uses the attributes 'only_from' to limit connections from a limited set of remote hosts and 'banner_fail' to print a suitable error message when access is denied

However, I can't find suitable 'equivalents' with systemd socket/service files on CentOS 7

It appears later versions of systemd supports the option IPAddressAllow= (which is what I think I need ?)

Does anyone know how to limit the remote hosts that can connect to a port with CentOS 7's systemd ?

Also, how to implement the equivalent of 'banner_fail' ? (not absolutely required, but nice to have)

I managed to do what is needed by creating a simple ExecStartPre script that checks if the $REMOTE_ADDR env var is in a list of my 'only_from' IP addresses - and exits with zero if it is or exits with non-zero if not

The non-zero status from the ExecStartPre script causes the whole service instance to fail

The ExecStartPre script also writes my 'banner_fail' message to stdout when it fails - which is what I want

Thanks for taking time to tell us about the solution.

/Peter